1. Field of the Invention
The invention relates to an improved register and sender arrangement for a telephone communication switching system, and more particularly to an arrangement of four registers and two senders in a single module which allows a sharing of certain functions such as digit storage, clock circuits, and address decoding.
2. Description of the Prior Art
The invention was developed for the system shown in U.S. Pat. No. 3,767,863, issued Aug. 23, 1973, by Borbas et al. for a Communication Switching System with Modular Organization and Bus, hereinafter referred to as the System S2 patent. A bus control arrangement including bus interface units is shown in U.S. Pat. No. 3,812,297, issued May 21, 1974, by Borbas for a Bus Control Arrangement for a Communication Switching System, hereinafter referred to as the BCU patent.
A previous system is described in U.S. Pat. No. 3,487,173, issued Dec. 30, 1969, by Duthie et al. for a Small Exchange Stored Program Switching System, hereinafter referred to as the System S1 patent. The register and sender arrangement of the S1 System is disclosed in U.S. Pat. No. 3,749,844, issued July 31, 1973, By Dufton for a Stored Program Small Exchange with Registers and Senders.
The S1 System register and sender arrangement was designed with each register and sender having its own storage facilities and therefore requiring separate addressing and access circuitry for each of the registers and senders. Other previous crossbar systems have also been arranged in a similar manner, however for the System S2 and future developments it was felt that flexibility and ease of expansion was a necessity. By providing an internal bus structure and progress word it was then possible to develop a system with increased flexibility which was also more economical. Registers and senders could be added by plugging in on an as required basis and different types of registers and senders could be utilized in a system.